Nonlinear Model Predictive Control of a Diesel Engine Air Path: A Comparison of Constraint Handling and Computational Strategies

This paper presents the development of a Nonlinear Model Predictive Controller (NMPC) for the diesel engine air path. The objective is to regulate the intake manifold pressure (MAP) and compressor ow (MAF) to the specified set-points by coordinated control of the variable geometry turbine (VGT), and exhaust gas recirculation (EGR) valve. The use of NMPC for the diesel engine air path is motivated by the ability of the controller to deal with nonlinear engine dynamics and handle input and output constraints. However, the Engine Control Unit (ECU) has limited computational resources and the addition of constraints can greatly increase the computational complexity of NMPC. A comparative assessment of the computation time and constraint violation for different constraint handling techniques is presented. The ability of NMPC to regulate MAP and MAF to specified set-points and to enforce constraints is demonstrated through nonlinear model simulations over the New European Drive Cycle (NEDC).